Fig. 1.

The time dependence of the detected cases for the different US states during the initial period of the epidemic is shown on a log-linear scale. The linear fit of log(D) shows that the spread of COVID-19 is well approximated by exponential growth in this phase. Values on axes are chosen differently for each state to emphasize the exponential growth phase. For each state, the start and end dates, the extracted slope λ₊, of the exponential regime, are given in Supplementary Table S1. Al – Alabama; AK – Arkansas; AR – Arizona; CA – California; CO – Colorado; FL – Florida; GA – Georgia; ID – Idaho; ME – Maine; MD – Maryland; MN – Montana; NE – Nebraska; NJ – New Jersey; NM – New Mexico; NY – New York; NC – North Carolina; OH – Ohio; OR – Oregon; PA – Pennsylvania; RI – Rhode Island; SD – South Dakota; TN – Tennessee; TX – Texas; VA – Virginia.